Friction spinning drum

ABSTRACT

In the manufacture of friction spinning drums, in order to be able to select the size of the holes or perforations, on the one hand, to oppose technological fiber loss and jamming of sucked in foreign particles and, on the other hand, to provide airflow advantages, it is proposed to manufacture the friction spinning drum from a thick-walled support and a thin-walled perforated body. As a result, holes or perforations having a sufficiently small cross-section to counteract the above-mentioned fiber loss can be formed in the thin-walled perforated body. On the other hand, holes or perforations having a large enough cross-section to prevent jamming of sucked in foreign particles or other contaminants can be provided in the thick-walled support.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to the commonly assigned, copending U.S.application Ser. No. 07/117,841, filed Nov. 9, 1987, and entitled"METHOD FOR MANUFACTURING A PERFORATED BODY, FRICTION SPINNING MEANSUSING THE PERFORATED BODY AND A FRICTION SPINNING DEVICE USING THEFRICTION SPINNING MEANS", and the commonly assigned, co-pending U.S.application Ser. No. 07/119,497, filed Nov. 12, 1987, and entitled "OPENEND FRICTION SPINNING DEVICE FOR PRODUCTION OF A YARN OR THE LIKE ANDMETHOD FOR PRODUCTION OF FRICTION SPINNING MEANS" the disclosures ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a new and improved construction of afriction spinning drum of the type comprising a hollow perforated drumdesigned for substantially radial throughflow of air.

Such friction spinning drums are used in known friction spinningprocesses or methods in which usually two cylindrical drums arrangedadjacent each other rotate in the same direction, at least one of thetwo drums being a perforated drum as above described.

The purpose of such perforated drum is to take up fibers fed thereto inknown manner by means of an airstream and to twist them into a yarn inthe region of convergence of the two friction spinning drums. The yarnis withdrawn in a direction substantially at right angles to thedirection of rotation of the friction spinning drums.

The airstream required to feed the fibers is drawn through the holes orperforations of the perforated drum by means of a suction nozzleprovided in the interior of such perforated drum.

It therefore should be manifest that, on the one hand, the holes orperforations of the perforated drum must have a diameter whichsubstantially prevents too many fibers being taken up or engaged by theholes or perforations during deposition on the perforated drum and thenbeing either sucked away and hence lost, or at least being cut on theedge of the mouth of the suction nozzle and thereby undesirablyshortened.

On the other hand, the energy consumption of such equipment must be heldas low as possible, the airflow representing a significant proportion ofthe energy consumption. From this standpoint, it is desirable to designthe holes or perforations of the perforated drum with the largestpossible diameter to present the lowest possible resistance to therequired throughflow quantity of air per unit time.

These two requirements placed on the diameter of the holes orperforations are diametrically opposed to each other.

In normal practice, and from patent publications, it is known that theseholes or perforations generally have a diameter between 0.5 and 0.8 mm.

On the other hand, the perforated drums must have inherent stiffness orrigidity in order to avoid deformation during use, thereby requiring aminimum wall thickness of at least 1.5 mm in such perforated drums whenmade of brass with, for example, a drum diameter of 50 mm.

It is, however, clear that boring or otherwise fabricating such smallholes in a material of 1.5 mm thickness or greater cannot be carried outwithout problems. Thus such operation is therefore expensive,particularly when the number of holes or perforations per perforateddrum is of the order of several tens of thousands.

When additional demands are placed on the configuration or form of theholes or perforations, as disclosed in the German Published Pat. No.2,919,316, the manufacturer of such perforated drums is confronted withspecial problems.

SUMMARY OF THE INVENTION

Therefore, with the foregoing in mind, it is a primary object of thepresent invention to provide a new and improved construction of afriction spinning drum which is not afflicted with the aforementioneddrawbacks and shortcomings of the prior art.

Another important object of the present invention is to provide a newand improved construction of a perforated drum which can be manufacturedeconomically with adequate inherent stiffness or rigidity and lowairflow resistance.

Yet a further significant object of the present invention resides ineconomically fabricating a friction spinning drum composed of two partswherein the holes or perforations of the friction spinning drum areparticularly structured to comply as well as possible with theconflicting demands of reduced airflow resistance through the holes orperforations and avoidance to the extent possible of undesired suckingin or engagement of the fibers deposited upon the outer surface or fiberreceiving surface of the friction spinning drum.

Now in order to implement these and still further objects of theinvention, which will become more readily apparent as the descriptionproceeds, the friction spinning drum of the present development ismanifested by the features that it comprises an inner perforated supportbody or support and an outer perforated body secured thereto.

Advantageously, the holes or perforations of the inner perforatedsupport body exhibit a larger cross-sectional area or cross-section thanthat of the holes or perforations of the outer perforated body.Furthermore, it is advantageous for the manufacturing operation if theinner perforated support body comprises a rigid hollow body or bodymember and the outer perforated body is a flexible body or body membermounted on the inner perforated support body. This outer perforated bodyor body member can comprise a metal band mounted on the inner perforatedsupport body in a spiral or helical configuration, or a rectangular foilmounted on the inner perforated support body. Equally, the outerperforated body can be mounted on the inner perforated support body inthe form of a tubular foil.

The holes or perforations in the inner perforated support body and theholes or perforations in the outer perforated body can be coaxiallyarranged.

Certain of the more notable advantages of the present invention residein the features that, on the one hand, the small diameter holes orperforations, which are difficult to fabricate, can be formed in arelatively thin or thin-walled material while the relatively thick orthick-walled support body or body member can be provided with holes orperforations which have a cross-section or cross-sectional area which isselected more appropriately in accordance with the greater wallthickness.

A further advantage of the present invention resides in the fact thatthe outer perforated body or body member can be constituted by a band orfoil capable of being mounted or drawn on (even when a foil in a secondoperation is joined to make up a tubular perforated body). The side ofthe perforated foil having burrs or the like can then be arranged as theexternal face or surface of the outer perforated body. If a galvaniccoating is then subsequently applied, this affords the further advantagethat the holes or perforations widen or enlarge from the outside towardsthe inside. This hole widening or enlargement is advantageous not simplyin relation to the pneumatic resistance of the individual hole orperforation; dirt particles which possibly penetrate into one of theholes or perforations cannot jam in the adjoining hole or perforationsection or region.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those setforth above will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein throughout the various figures of thedrawings, there have been generally used the same reference charactersto denote the same or analogous components and wherein:

FIG. 1 illustrates a front view of a friction spinning drum constructedin accordance with the present invention;

FIG. 2 illustrates an enlarged detail of the region of the frictionspinning drum within the circle A depicted in FIG. 1 and illustrated insectional view;

FIG. 3 illustrates an enlarged detail of the region of the frictionspinning drum within the circle B depicted in FIG. 1 and taken from thesurface of the friction spinning drum of FIG. 1;

FIG. 4 illustrates a modification of the surface of the frictionspinning drum shown in FIG. 3; and

FIGS. 5, 6 and 7 illustrate respective views of possibilities of use ofa friction spinning drum according to FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Describing now the drawings, it is to be understood that to simplify theshowing thereof, only enough of the structure of the friction spinningdrum has been illustrated therein as is needed to enable one skilled inthe art to readily understand the underlying principles and concepts ofthe present invention. Turning now specifically to FIG. 1 of thedrawings, the friction spinning drum 1 illustrated therein by way ofexample and not limitation, will be seen to comprise an inner supportbody or body member 2 with an outer perforated or sieve body or bodymember 3 mounted thereon. The form or structure of this outer perforatedbody or body member 3 will be described hereinafter.

The inner support body or body member 2 is designed as a hollow body andis firmly connected at one end with a stub-shaft 4 or equivalentstructure. A shaft 5 operatively associated with the stub-shaft 4 servesto receive a roller bearing 6 or the like by means of which the frictionspinning drum 1 is rotatably supported. As a means for driving thefriction spinning drum 1 there can be provided, for instance, a drivebelt 7 which engages the shaft 5.

As shown in sectional view in FIG. 1, the outer perforated body 3 hasholes or perforations 8 and the inner support body 2 has throughbores orthroughholes 9. A suction nozzle 10 or equivalent structure provided atthe opposite axial end of the friction spinning drum 1 projects in knownmanner into the inner support body 2 and draws or sucks in air throughthe holes or perforations 8 and throughbores or throughholes 9 by meansof a suitable nozzle mouth (not shown) of the suction nozzle 10 andwhich suction nozzle mouth is arranged close to the cylindrical internalwall of the inner support body or body member 2. This suction nozzle orsuction arrangement 10 is well known from friction spinning technologyand is therefore not here described in further detail, particularlysince such is unimportant in terms of the teachings and the principlesof the present invention.

The holes or perforations 8 and the throughbores or throughholes 9 arerespectively provided in the inner support body 2 and the outerperforated body 3 within a perforated region as indicated in dot-dashlines. The holes or perforations 8 and the throughbores or throughholes9 collectively form the holes or perforations 8,9 of the perforatedfriction spinning drum 1.

FIG. 2 shows a detail of the inner support body 2 and the outerperforated body 3 indicated at the region of the friction spinning drum1 enclosed within the circle A in FIG. 1. The wall thickness of theinner support body 2 is designated W and the wall thickness of the outerperforated body 3 is designated V.

It is further apparent that the manufacturing burrs 11 (which have beenexaggerated for clarity of illustration and comprehension) are directedtowards the exterior or outer surface of the friction spinning drum 1.Further, the outer perforated body 3 is coated on its outer cylindricalsurface, defining a fiber receiving surface, with a galvanic coating orlayer 12, which may be roughened in any suitable manner, and which forphysical reasons builds up more strongly around the burrs 11 than in theadjacent surface portions or regions. In addition, with a coatingthickness which is predetermined in relation to the wall thickness V ofthe outer perforated body 3, the galvanic coating 12 also builds up, asshown in FIG. 2, in such manner in the depth of the holes orperforations 8 that such holes or perforations take on a form similar toa diffusor. This affords the advantages discussed in the introductoryportion of this disclosure, namely that, on the one hand, thediffusor-like form or configuration provides an airflow advantage and,on the other hand, dirt particles or other contaminants sucked into theholes or perforations 8 cannot jam therein.

A further advantage of the stronger or more pronounced build-up of thegalvanic coating 12 or the like around the manufacturing burrs 11 isthat a small annular projection is created around each hole orperforation 8. This desirably improves the friction properties of theouter or fiber receiving surface of the outer perforated body 3.

The wall thickness W (FIG. 2) of an inner support body 2 made of, forinstance, brass can, for example, lie in the range 1.5 to 2 mm, and thewall thickness V of an outer perforated body 3 made of, for instance,nickel-chrome alloy can be 0.5 to 0.8mm. The thickness of the galvaniccoating 12 is about 0.2 mm in the surface regions between the annularprojections. There also may be applied a plasma coating or layer uponthe galvanic coating or layer 12.

Further, it will be seen from FIGS. 2 and 3 that the throughbores orthroughholes 9 have a larger cross-section or cross-sectional area thanthe smallest cross-section or cross-sectional area of a hole orperforation 8. In the case where the holes or perforations 8 are round,the smallest cross-section or cross-sectional area of each hole orperforation 8 can, for example, have a diameter of 0.5 mm and thediameter of the throughbore throughhole 9 can be 0.8 to 1mm, dependingupon the hole spacing, so that the inner support body 2 still providessufficient material between the throughbores or througholes 9 to enableit to fulfill its purpose as regards strength.

This affords the advantage that, as a result of the small wall thicknessV, the holes or perforations 8 of the outer perforated body 3 can bebored or otherwise appropriately machined without problems usingconventional boring, punching or electron beam boring technology. As aresult of their significantly greater diameter, the throughbores orthroughholes 9 of the inner support body 2 can be bored without problemsusing conventional boring techniques even when the wall thickness is 2mm or more.

As is also apparent from FIGS. 2 and 3, the holes or perforations 8 arearranged coaxially with respect to the throughbores or throughholes 9,although this is not absolutely necessary. It is possible to usesignificantly larger throughbores or throughholes 9 which do not havethe same gauge as the holes or perforations 8; the term "gauge" refersin this disclosure to the spacing of the hole centers.

Furthermore, the sum of all cross-sectional areas of the holes orperforations 9 in the inner support body 2 represents a greaterproportion of the total surface of the perforated region a than the sumof all cross-sectional areas of the holes or perforations 8 of the outerperforated body 3.

In addition, it can be seen from FIG. 4 that the holes or perforations 8in the outer perforated body 3 do not necessarily have to have a roundsection. Other hole forms or configurations are possible, especiallywhen a punching technique is used during manufacture. In FIG. 4,four-sided holes or perforations 8 have been shown, but holes orperforations with other forms could also be used. The same applies tothe throughbores or throughholes 9 in the event that another fabricationtechnique is used in place of boring to produce the throughbores orthroughholes 9 in the inner support body 2, for example injectionmolding.

FIGS. 5, 6 and 7 show various ways in which the outer perforated body 3can be formed and mounted on the inner support body 2.

FIG. 5 illustrates an outer perforated body, here designated byreference character 3a, in a band-form, for instance formed of anysuitable metal, and which is spirally or helically wound on the innersupport body 2 and connected thereto by any suitable connecting means.The connection can be effected, for example, by a suitable adherance oradhesion technique in that the start and finish of the band-form orband-shaped outer perforated body 3a is adhesively bonded to the innersupport body 3 in the zones located outside the perforated region a. Thespiral winding is carried out in such manner that the turns or coils 30of the band-shaped outer perforated body 3a contact or abut each otherin order to prevent throughflow of air at the region of the joins orjoints 13. Furthermore, there exists the possibility of welding the bandturns or coils 30 together at the region of the joins or joints 13 by alaser beam.

In FIG. 6, the outer perforated body, here designated by referencecharacter 3b, consists of a rectangular foil 32 mounted on the innersupport body 2 and engaging sealingly thereon without forming any spacesat the joins or joints 14. Furthermore, the joins or joints 14 can alsobe welded by means of a laser beam.

In FIG. 7, the outer perforated body, here designated by referencecharacter 3c, comprises a hollow body 34, such as a tubular foil, madeof a material having a lower coefficient of expansion than the innersupport body 2, i.e. since the selection of the material for the outerperforated body 3c takes precedence, the material of the inner supportbody 2 is selected to exhibit a greater coefficient of expansion thanthe outer perforated body 3c. For mounting of the outer perforated body3c, such outer perforated body 3c and the inner support body 2 arecooled to a temperature substantially below normal ambient so that theinner support body 2 shrinks during cooling to a greater extent than theouter perforated body 3c. This enables problem-free mounting of theouter perforated body 3c on the inner support body 2. The externaldiameter of the inner support body 2 is so selected in comparison to theinternal diameter of the outer perforated body 3c that upon warming tonormal temperature (not as high as operating temperature) the outerperforated

3c seats firmly and without rotation on the inner support body 2. Duringwarming to operating temperature, a predetermined pretension isgenerated in the outer perforated body 3c.

The manufacture of a hollow body of this type can be performedgalvanically and is disclosed in the previously mentioned commonlyassigned, copending U.S. application Ser. No. 07/117,841, filed Nov. 9,1987, and entitled "METHOD FOR MANUFACTURING A PERFORATED BODY, FRICTIONSPINNING MEANS USING THE PERFORATED BODY AND A FRICTION SPINNING DEVICEUSING THE FRICTION SPINNING MEANS"

While there are shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto, but may be otherwise variously embodied and practicedwithin the scope of the following claims. ACCORDINGLY,

What we claim is:
 1. A friction spinning drum comprising:a hollowperforated drum structured for substantially radial throughflow of air;said hollow perforated drum comprises an inner perforated support bodyand an outer perforated body; and said outer perforated body constitutesa separate sieve body which is mounted upon and rotatable with saidinner perforated support body.
 2. The friction spinning drum as definedin claim 1, wherein:said inner perforated support body has holes; saidouter perforated body has holes; and the holes of the inner perforatedsupport body have a large cross-sectional area than the holes of theouter perforated body.
 3. The friction spinning drum as defined in claim2, wherein:the holes of the inner perforated support body and the holesof the outer perforated body are disposed substantially coaxially withrespect to one another and collectively define perforations of thehollow perforated drum.
 4. The friction spinning drum as defined inclaim 2, wherein:the sum of the cross-sectional areas of the holes ofthe inner perforated support body constitutes a greater proportion of apredeterminate total surface of a perforated region of the innerperforated support body than the sum of the cross-sectional areas of theholes of the outer perforated body.
 5. The friction spinning drum asdefined in claim 2, wherein:the holes of the outer perforated bodycontain burrs surrounding said holes; and the outer perforated body ismounted on the inner perforated support body such that said burrssurrounding the holes of the outer perforated body are located on anexternal surface of said outer perforated body.
 6. The friction spinningdrum as defined in claim 1, wherein:the inner perforated support bodycomprises a rigid hollow body; and the outer perforated body comprises aspiral metal band mounted on the inner perforated support body.
 7. Thefriction spinning drum as defined in claim 1, wherein:the outerperforated body comprises a spiral metal band mounted on the innerperforated support body.
 8. The friction spinning drum as defined inclaim 1, wherein:the outer perforated body comprises a substantiallyrectangular foil mounted on the inner perforated support body.
 9. Thefriction spinning drum as defined in claim 1, wherein:the outerperforated body comprises a substantially tubular foil mounted on theinner perforated support body.
 10. The friction spinning drum as definedin claim 1, wherein:the outer perforated body has an outer surface; anda coating provided on the outer surface of the outer perforated body.11. The friction spinning drum as defined in claim 10, wherein:saidcoating provided on the outer surface of the outer perforated bodycomprises a galvanic coating.
 12. The friction spinning drum as definedin claim 11, wherein:the galvanic coating constitutes a roughenedgalvanic coating.
 13. The friction spinning drum as defined in claim 10,wherein:the coating provided on the outer surface of the outerperforated body comprises a galvanic coating and a plasma coatingapplied onto said galvanic coating.
 14. A friction spinning drumcomprising:a hollow perforated drum structured for substantially radialthroughflow of air; said hollow perforated drum comprises an innerperforated support body and an outer perforated body; said outerperforated body constitutes a separate, sieve body which is mounted uponand rotatable with said inner perforated support body; said innerperforated support body has holes; said separate sieve body has holes;and the holes of the inner perforated support body have a largercross-sectional area with respect to minimizing air flow resistance thanthe smaller cross-sectional area of the holes of the separate sieve bodydimensioned with respect to minimizing fiber loss and damage.